Heated showerhead assembly

ABSTRACT

The present invention generally comprises a heated showerhead assembly that may be used to supply processing gases into a processing chamber. The processing chamber may be an etching chamber. When processing gas is evacuated from the processing chamber, the uniform processing of the substrate may be difficult. As the processing gas is pulled away from the substrate and towards the vacuum pump, the plasma, in the case of etching, may not be uniform across the substrate. Uneven plasma may lead to uneven etching. To prevent uneven etching, the showerhead assembly may be separated into two zones each having independently controllable gas introduction and temperature control. The first zone corresponds to the perimeter of the substrate while the second zone corresponds to the center of the substrate. By independently controlling the temperature and the gas flow through the showerhead zones, etching uniformity of the substrate may be increased.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a heatedshowerhead assembly.

2. Description of the Related Art

Integrated circuits have evolved into complex devices that can includemillions of components (e.g., transistors, capacitors, resistors, andthe like) on a single chip. The evolution of chip designs continuallyrequires faster circuitry and greater circuit density. The demands forgreater circuit density necessitate a reduction in the dimensions of theintegrated circuit components. The minimal dimensions of features ofsuch devices are commonly referred to in the art as critical dimensions.The critical dimensions generally include the minimal widths of thefeatures, such as lines, columns, openings, spaces between the lines,and the like.

As these critical dimensions shrink, process uniformity across thesubstrate becomes paramount to maintain high yields. One problemassociated with a conventional plasma etch process used in themanufacture of integrated circuits is the non-uniformity of the etchrate across the substrate, which may be due, in part, to a vacuum pumpdrawing the etching gas toward the exhaust port and away from thesubstrate. As gases are more easily pumped from areas of the chamberthat are closest to the exhaust port (i.e., the periphery of thesubstrate), the etching gas is pulled toward the exhaust port and awayfrom the substrate, thereby creating a non-uniform etch on the substratepositioned therein. This non-uniformity may significantly affectperformance and increase the cost of fabricating integrated circuits.

Therefore, there is a need in the art for an apparatus for uniformlyetching material layers during the manufacture of integrated circuits.

SUMMARY OF THE INVENTION

The present invention generally comprises a heated showerhead assemblythat may be used to supply processing gases into a processing chamber.In one embodiment, a showerhead, comprises a showerhead body having afirst zone encircling a second zone. The first zone comprises a firstplenum disposed on a first side of the body, one or more second plenumsdisposed on the second side of the body, and a plurality of first boresarranged in a plurality of first annular patterns, the plurality offirst bores extending from the first plenum to the one or more secondplenums. The second zone comprises a third plenum disposed on the firstside of the body, one or more fourth plenums disposed on the second sideof the body, and a plurality of second bores arranged in a plurality ofsecond annular patterns, the plurality of second bores extending fromthe third plenum to the one or more fourth plenums.

In another embodiment, a showerhead assembly comprises a first gasdistribution plate having a first side, a second side, and two or morezones, each zone having a plurality of first bores extending through thefirst gas distribution plate from the first side to the second side, anda second gas distribution plate having a third side, a fourth side, anda plurality of second bores extending from the third side to the fourthside through the second gas distribution plate, wherein the third sideof the second gas distribution plate coupled with the second side of thefirst gas distribution plate, and the number of second bores exceeds thenumber of first bores.

In another embodiment, a method of refurbishing a showerhead comprisesdisassembling a first showerhead body from a second showerhead body,cleaning at least the first showerhead body, and bonding the firstshowerhead body to a third showerhead body. The first showerhead bodyhas a first zone encircling a second zone. The first zone comprises afirst plenum disposed on a first side of the first showerhead body, oneor more second plenums disposed on the second side of the firstshowerhead body, and a plurality of first bores arranged in a pluralityof first annular patterns, the plurality of first bores extending fromthe first plenum to the one or more second plenums. The second zonecomprises a third plenum disposed on the first side of the firstshowerhead body, one or more fourth plenums disposed on the second sideof the first showerhead body, and a plurality of second bores arrangedin a plurality of second annular patterns, the plurality of second boresextending from the third plenum to the one or more fourth plenums.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic cross sectional view of an etching apparatusaccording to one embodiment of the invention.

FIG. 2A is a schematic cross sectional view of a showerhead assembly 200according to one embodiment of the invention.

FIG. 2B is a close up view of the inner zone 218 of FIG. 2A.

FIG. 2C is a close-up view of the interface between the first diffuserplate 214 and the second diffuser plate 216.

FIG. 2D is a bottom view of the first diffuser plate 214 shown in FIG.2A.

FIG. 3 is a schematic top view of a showerhead assembly 300 according toone embodiment of the invention.

FIG. 4 is a schematic bottom view of a showerhead assembly 400 accordingto one embodiment of the invention.

FIG. 5 is a flow chart showing the process steps of a refurbishmentmethod according to one embodiment of the invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

The present invention generally comprises a heated showerhead assemblythat may be used to supply processing gases into a processing chamber.The processing chamber may be an etching chamber. When processing gas isevacuated from the processing chamber, the uniform processing of thesubstrate may be difficult. As the processing gas is pulled away fromthe substrate and towards the vacuum pump, the plasma, in the case ofetching, may not be uniform across the substrate. Uneven plasma may leadto uneven etching. To prevent uneven etching, the showerhead assemblymay be separated into two zones each having independently controllablegas introduction and temperature control. The first zone corresponds tothe perimeter of the substrate while the second zone corresponds to thecenter of the substrate. By independently controlling the temperatureand the gas flow through the showerhead zones, etching uniformity of thesubstrate may be increased.

The invention will be described below in relation to an etching chamber.However, a variety of plasma deposition and etching chambers may benefitfrom the teachings disclosed herein, and in particular, dielectricetching chambers such as the ENABLER® etch chamber, which may be part ofa semiconductor wafer processing system such as the CENTURA® system, thePRODUCER® etch chamber, the eMax® etch chamber, among others, all ofwhich are available from Applied Materials, Inc. of Santa Clara, Calif.It is contemplated that other plasma reactors, including those fromother manufacturers, may be adapted to benefit from the invention.

FIG. 1 is a schematic cross sectional view of an etching apparatusaccording to one embodiment of the invention. The apparatus comprises achamber 100 having a plurality of walls 102 extending upwards from achamber bottom 104. Within the chamber 100, a susceptor 106 is presentupon which a substrate 108 may be supported for processing. Thesubstrate 108 may be introduced into the chamber 100 through a slitvalve opening 120.

The chamber 100 may be evacuated by a vacuum pump 112 coupled to thechamber wall 102 through a vacuum port 156. The chamber 100 may beevacuated by drawing the processing gas around and through a baffle 110that circumscribes the susceptor 106 and substrate 110. The further awayfrom the vacuum pump 112, the less the draw of the vacuum may bedetected. Conversely, the closer to the vacuum pump 112, the greater thedraw of the vacuum that may be detected. Thus, to compensate for anuneven vacuum draw, a flow equalizer 116 may be disposed within thechamber 100. The flow equalizer 116 may circumscribe the susceptor 106.The width of the flow equalizer 116 may be smaller at the locationfurther away from the vacuum port 156 as shown by arrows “B” compared tothe width of the flow equalizer 116 at a location closest to the vacuumport 156 as shown by arrows “C”. The gas being evacuated may flow aroundthe flow equalizer and then through a lower liner 114. The lower liner114 may have one or more holes therethrough to permit the processing gasto be evacuated therethrough. A space 118 is present between the lowerliner 114 and the walls 102 of the chamber 100 to permit the gas to flowbehind the lower liner 114 to the vacuum port 156. The vacuum port 156may be blocked by a flow blocker 154 to prevent processing gas frombeing drawn directly into the vacuum pump 112 from an area close to thesubstrate 108. The evacuated gas may flow along a path shown by arrows“A”.

Processing gas may be introduced into the processing chamber 100 througha showerhead 122. The showerhead 122 may be biased by an RF current froman RF power source 152, and the showerhead 122 may comprise a firstdiffuser plate 126 and a second diffuser plate 124. In one embodiment,the first diffuser plate 126 may comprise aluminum. In anotherembodiment, the second diffuser plate 124 may comprise silicon carbide.The first diffuser plate 126 and the second diffuser plate 124 may bebonded together. In one embodiment, the first diffuser plate 126 and thesecond diffuser plate 124 may be welded together. In another embodiment,the first diffuser plate 126 and the second diffuser plate 124 may bebonded together utilizing an elastomer. The showerhead 122 may bedivided into an inner zone 158 and an outer zone 160. The inner zone 158may have a heating element 128. In one embodiment, the heating element128 may have an annular shape. The heating element 128 may be coupledwith a heating source 148. The outer zone 160 may also comprise aheating element 130 coupled with a heating source 150. In oneembodiment, the heating elements 128, 130 may comprise annular conduitsthat are filled with a heating fluid from the heating sources 148, 150.In another embodiment, the heating elements 128, 130 may compriseheating coils powered by the heating sources 148, 150. While not shown,thermocouples may provide real time temperature feedback to a controllerthat controls the amount of heat supplied to the inner zone 158 and theouter zone 160.

The inner zone 158 may be coupled with a gas source 138 by a conduit146. Gas from the gas source 138 may flow through the conduit 146 to aplenum 132 disposed behind the first diffuser plate 126 of theshowerhead 122. A valve 142 may be disposed along the conduit 146 tocontrol the amount of gas that flows from the gas source 138 to theplenum 132. Once the gas enters the plenum 132, the gas may then passthrough the diffuser plates 124, 126. Similarly, the outer zone 160 maybe coupled with a gas source 138 by a conduit 144. A valve 140 may bedisposed along the conduit 144 to control the amount of gas that flowsfrom the gas source 136 to the plenum 134.

It is to be understood that while separate gas sources 136, 138 havebeen shown in FIG. 1, a single, common gas source may be utilized. Whena single common gas source is utilized, separate conduits 144, 146 maybe coupled to the gas source and the valves 140, 142 may control theamount of processing gas that reaches the plenums 132, 134.

FIG. 2A is a schematic cross sectional view of a showerhead assembly 200according to one embodiment of the invention. The showerhead assembly200 comprises a backing plate 212 coupled to a first diffuser plate 214and a second diffuser plate 216. The showerhead assembly 200 comprisesan inner zone 218 and an outer zone 220. The inner zone may be coupledto a heating source 222 that provides heat for the heating element 226.A gas source 204 may also be coupled with the inner zone 218 through aconduit 208. A valve 210 may be coupled along the conduit 208 to controlthe amount of processing gas provided to the plenum 230. The inner zone218 and the outer zone 220 may be annular. A heating source 224 may alsobe coupled with the heating element 228 of the outer zone 220. A gassource 202 may be coupled with the plenum 232 of the outer zone 220through a conduit 206. A valve 210 along the conduit 206 may control theamount of processing gas that reaches the plenum 232.

FIG. 2B is a close up view of the inner zone 218 of FIG. 2A. Theprocessing gas that enters the plenum 230 is evenly distributed withinthe plenum because of the orifice holes 238. The orifice holes 238 aresized to create an even distribution of process gas among the gaspassages 246 of the first diffuser plate 214. The orifice holes 238 mayhave a diameter shown by arrows “D”. Because the diameter of the orificeholes 238 is smaller than the plenum 230, processing gas may build upwithin the plenum and a substantially equal amount of processing gas maypass through the orifice hole 238. Once through the orifice holes, theprocessing gas may expand in first expanding channels 240. The firstexpanding channels 240 may have diameter as shown by arrows “E”. Thediameter of the first expanding channels 240 is greater than thediameter the orifice hole 238. The processing gas enters secondexpanding channels 242 after passing through the first expandingchannels 240. The second expanding channels 242 have a width as shown byarrows “F”.

The second diffuser plate 216 also comprises a plurality of gas passages244. The gas passages 244 are coupled with the second expanding channels242 of the first diffuser plate 214 such that each second expandingchannel 242 forms at least one annular plenum for flowing a gas into thegas passages 244. The gas passages 244 of the second diffuser plate 216each have a width or diameter as shown by arrows “G”. The width ordiameter of the gas passages 244 is less than the width or diameter ofthe second expanding channels 242. The second expanding channels 242 mayact as a plenum for the gas passages 244 of the second diffuser plate216. As the width or diameter of each gas passage 244 is substantiallythe same, the processing gas may evenly distribute within the secondexpanding channels 242 before entering the gas passages 244. Thus, asubstantially equal amount of processing gas may flow through each gaspassage 244. The gas passages 244, 246 may be bored into the diffuserplates 214, 216. The gas passages 244 collectively are arranged in anannular pattern around the diffuser plate 216. In one embodiment, thewidth of the annular pattern of gas passages 244 is substantially equalto the width of the second expanding channels 242.

The first diffuser plate 214 may be bonded to the second diffuser plate216. In one embodiment, the first diffuser plate 214 may be anodized andthen bonded to the second diffuser plate 216. In one embodiment, thebonding material 248 may comprise a silicone based bonding material.FIG. 2C is a close-up view of the interface between the first diffuserplate 214 and the second diffuser plate 216. As shown in FIG. 2C, thebottom surface of the first diffuser plate 214 has a plurality ofexpanding channels 242 into which processing gas will expand beforeentering the second diffuser plate 216. Each of the gas passages 246that are arranged in an annular pattern feed into a common expandingchannel 242. The expanding channel 242 may permit the processing gas toevenly distribute and then enter the gas passages 244 of the seconddiffuser plate 216. In one embodiment, each expanding channel 242 is anannular groove bored into the bottom surface of the first diffuser plate214. FIG. 2D is a bottom view of the first diffuser plate 214 shown inFIG. 2A. The gas passages 246 of the first diffuser plate 214 may feedinto an expanding channel 242 where the gas may evenly distribute beforeentering the gas passages 244 of the second diffuser plate 216.

One or more bonding grooves 250 may be bored into the first diffuserplate 214. The bonding grooves 250 may be annular channels disposedbetween adjacent expanding channels 242. The bonding grooves 250 mayhave a height as shown by arrows “L”. In one embodiment, the height ofthe bonding grooves 250 may be less than the height, as shown by arrows“N”, of the expanding channel 242. In another embodiment, the height ofthe bonding grooves 250 may be substantially equal to the height of theexpanding channel 242. A space 252 may remain between the first diffuserplate 214 and the second diffuser plate 216. The space 252 may bedisposed between the expanding channel 242 and the adjacent bondinggroove 250. If the space 252 is too small, particles can be trappedtherein. If the space 252 is too large, then too much bonding material248 is exposed to the processing gas and may be attacked by theprocessing gas to break down the bonding material 248. The space 252 mayhave a height as shown by arrows “M” that is sufficiently small toreduce any bonding material 248 that may be exposed to processing gasduring processing, from escaping and passing through the gas passages244 of the second diffuser plate 216. In one embodiment, the height ofthe space 252 may be between about 0.005 inches to about 0.009 inches.It is to be understood that while the bonding grooves 250 have beenbored into the first diffuser plate 250, the bonding grooves 250 may bebored into the second diffuser plate 216 instead so long as the bondinggrooves 250 do not interfere with the gas passages 244 of the seconddiffuser plate 216 of compromise the structural integrity of the seconddiffuser plate 216.

Referring back to FIG. 2A, the inner zone 218 may have a plurality ofgas passages 246 through the first diffuser plate 214. In oneembodiment, five gas passages 246 may be present in the inner zone 218.The outer zone 220 may also have a plurality of gas passages 246 throughthe first diffuser plate 214. In one embodiment, three gas passages 246may be present in the outer zone 220. The number of gas passages 246within the inner zone 218 may be greater than the number of gas passages246 within the outer zone 220. It is to be understood that more or lessgas passages 246 may be utilized for the inner zone 218 and the outerzone 220 depending upon the flow characteristics of the particularchamber.

The gas flow through the inner zone 218 of the showerhead assembly 200may be greater than the gas flow through the outer zone 220 of theshowerhead assembly 200. When the vacuum is drawn in the processingchamber, the periphery of the substrate may be exposed to a greateramount of processing gas because the processing gas corresponding to thecenter of the substrate passes over the periphery of the substrate onthe way to the vacuum pump. By having a greater gas flow in the innerzone 218 of the showerhead assembly 200, the center of the substrate maybe exposed to a substantially equal amount of processing gas as theperiphery of the substrate.

The showerhead assembly 200 may be debonded by heating the showerheadassembly 200 to a temperature above the melting point of the bondingmaterial 248. Thereafter, the first diffuser plate 214 may be removedfrom the second diffuser plate 216 and the bonding material 248 removed.Both the first diffuser plate 214 and the second diffuser plate 216 maythen be cleaned. If either plate 214, 216 is beyond repair, the plate214, 216 may be replaced and rebonded to the other plate 214, 216. Inone embodiment, the first diffuser plate 214 may be reanodized. In oneembodiment, a cold debonding process may be used. The cold debondingprocess may comprise physically cutting the second diffuser plate 216from the first diffuser plate 214. The bonding material 248 may then beremoved from the diffuser plates 214, 216. In one embodiment, thebonding material 248 may be removed by etching. In another embodiment,the bonding material 248 may be removed by machining the bondingmaterial by a process such as grinding.

FIG. 3 is a schematic top view of a showerhead assembly 300 according toone embodiment of the invention. The showerhead assembly 300 comprisesan outer zone 302 and an inner zone 304. The outer zone 302 comprises aheating element 308, and the inner zone comprises a heating element 310.Within both the inner zone 304 and the outer zone 302, a plurality oforifice holes 306 are shown. Within the outer zone 302, the orificeholes 306 are arranged in three annular patterns. It is to be understoodthat while three annular patterns are shown, the orifice holes 306 maybe arranged in more or less annular patterns. Additionally, the orificeholes 306 may be randomly dispersed within the outer zone 302. In theembodiment shown, the annular patterns are spaced apart by a distanceshown by arrows “H”.

Within the inner zone 304, the orifice holes 306 are arranged in fiveannular patterns. It is to be understood that while five annularpatterns are shown, the orifice holes 306 may be arranged in more orless annular patterns. Additionally, the orifice holes 306 may berandomly dispersed within the inner zone 304. In the embodiment shown,the annular patterns are spaced apart by a distance shown by arrows “I”.The distance between the annular patterns of the outer zone 302 and theinner zone 304 is shown by the arrows “J”. In one embodiment, “J” issubstantially equal to “I” and substantially equal to “H”.

FIG. 4 is a schematic bottom view of a showerhead assembly 400 accordingto one embodiment of the invention. The showerhead assembly 400comprises a diffuser plate 402 having a plurality of annular patterns404. Within each annular pattern, are annular patterns of openings 406.While three annular patterns of openings 406 are shown in each pattern404, it is to be understood that more or less annular patterns ofopenings 406 may be present. Within the annular patterns 404, theannular patterns of openings 406 may be equally spaced apart. Theannular patterns 404 may be equally spaced apart a distance shown byarrows “K”. While eight annular patterns 404 are shown, it is to beunderstood that more or less annular patterns 404 may be present.

Once a showerhead assembly has been used for a length of time, theshowerhead assembly may become dirty, the gas passageways may becomeblocked, or the showerhead assembly may degrade such that continued useof the showerhead assembly may not be advisable. In some situations, theshowerhead assembly may be refurbished so that it may be used again.FIG. 5 is a flow chart 500 of a showerhead refurbishment methodaccording to one embodiment of the invention.

Initially, the showerhead assembly may be disassembled (Step 502). Thedisassembly comprises disassembling the first gas distribution platefrom the second gas distribution plate. The disassembly may comprisesimply pulling the plates apart, heating the assembly to a temperatureat or above the melting point of the material bonding the platestogether, or cutting the plates apart.

After the assembly is disassembled, the first and second gasdistribution plates are inspected (Step 504). The plates are inspectedto determine whether they are reusable after a suitable cleaning, orwhether they are damaged (Step 506). If a plate is damaged, uncleanable,or otherwise not usable, then the plate is discarded (Step 508) and athird or replacement plate is obtained (Step 510).

If one or more of the plates are cleanable, then the plate is cleaned(Step 512) to remove any bonding material from the plate as well as anymaterial that may have deposited on the plate or within the gaspassages. After the cleaning, the plate may need to be re-anodized (Step514). Thereafter, the cleaned plates may be rebounded together, or inthe case of a replacement plate, the cleaned plate may be bonded to thereplacement plate (Step 516).

A showerhead having an inner zone and an outer zone may be beneficial inetching processes. Individual gas supply and temperature control of thezones may permit a technician to control the plasma within theprocessing chamber and compensate for the vacuum drawn in the chamberduring processing.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A showerhead, comprising a showerhead body having: a first zoneencircling a second zone, wherein the first zone has: a first plenumdisposed on a first side of the body; one or more second plenumsdisposed on the second side of the body; and a plurality of first boresarranged in a plurality of first annular patterns, the plurality offirst bores extending from the first plenum to the one or more secondplenums; and the second zone has: a third plenum disposed on the firstside of the body; one or more fourth plenums disposed on the second sideof the body; and a plurality of second bores arranged in a plurality ofsecond annular patterns, the plurality of second bores extending fromthe third plenum to the one or more fourth plenums.
 2. The showerhead ofclaim 1, wherein the showerhead body comprises aluminum.
 3. Theshowerhead of claim 1, wherein the one or more second plenums arearranged in a plurality of third annular patterns that match theplurality of first annular patterns and the one or more fourth plenumsare arranged in a plurality of fourth annular patterns that match theplurality of second annular patterns.
 4. The showerhead of claim 1,wherein the first zone comprises a first heating element confinedtherein and the second zone comprises a second heating element confinedtherein.
 5. A showerhead assembly, comprising: a first gas distributionplate having a first side, a second side, and two or more zones, eachzone having a plurality of first bores extending through the first gasdistribution plate from the first side to the second side; and a secondgas distribution plate having a third side, a fourth side, and aplurality of second bores extending from the third side to the fourthside through the second gas distribution plate, the third side of thesecond gas distribution plate coupled with the second side of the firstgas distribution plate, and the number of second bores exceeds thenumber of first bores.
 6. The assembly of claim 5, wherein each zone ofthe two or more zones has one or more heat transfer elements.
 7. Theassembly of claim 6, wherein the one or more heat transfer elementscomprise heating coils.
 8. The assembly of claim 5, wherein the firstbores are arranged in one or more first annular patterns when viewedfrom the first side.
 9. The assembly of claim 8, wherein each zone has aplurality of annular patterns.
 10. The assembly of claim 8, wherein thefirst zone encircles the second zone.
 11. The assembly of claim 10,wherein the second zone has more annular patterns than the first zone.12. The assembly of claim 8, wherein the second bores are arranged inone or more second annular patterns when viewed from the fourth side.13. The assembly of claim 12, wherein the number of second bores in eachsecond annular pattern is greater than the number of first bores in eachfirst annular pattern.
 14. The assembly of claim 12, wherein the firstbores when viewed from the second surface have a width substantiallyequal to a width of the second annular pattern.
 15. The assembly ofclaim 5, wherein the first gas distribution plate comprises aluminum.16. The assembly of claim 5, wherein the second gas distribution platecomprises silicon carbide.
 17. The assembly of claim 5, wherein adiameter of the one or more first bores on the first side is less than adiameter of the one or more first bores on the second side.
 18. Theassembly of claim 5, wherein the bores in each zone extend from anannular plenum on the first side of the first gas distribution plate.19. The assembly of claim 18, wherein each bore extends to a circularplenum on the second side of the first gas distribution plate.
 20. Ashowerhead refurbishment method, comprising: disassembling a firstshowerhead body from a second showerhead body, the first showerhead bodyhaving a first zone encircling a second zone, wherein the first zonehas: a first plenum disposed on a first side of the body; one or moresecond plenums disposed on the second side of the body; and a pluralityof first bores arranged in a plurality of first annular patterns, theplurality of first bores extending from the first plenum to the one ormore second plenums; and the second zone has: a third plenum disposed onthe first side of the body; one or more fourth plenums disposed on thesecond side of the body; and a plurality of second bores arranged in aplurality of second annular patterns, the plurality of second boresextending from the third plenum to the one or more fourth plenums;cleaning at least the first showerhead body; and bonding the firstshowerhead body to a third showerhead body.
 21. The method of claim 20,wherein the second showerhead body and the third showerhead body are thesame showerhead body.
 22. The method of claim 21, further comprisingcleaning the second showerhead body.
 23. The method of claim 20, whereinthe first showerhead body comprises anodized aluminum, and the methodfurther comprises re-anodizing the first showerhead body prior tobonding.